1. Field of the Invention
The present invention relates to the field of semiconductor packaging, and more particularly, to a semiconductor package having a heat spreader which has a metal medium layer and an insulation layer coated thereon.
2. Description of Related Art
Because the semiconductor device is getting complicated in function and miniaturized in dimension, the heat generated by the semiconductor device is thus increased. To maintain the semiconductor device operate in a normal temperature range, FIG. 4 shows a semiconductor package which has a metal spreader (91) to assist in dissipating excess heat. The metal spreader (91) is typically made of copper that has a relative high thermal coefficient. Such a copper heat spreader (91) contacts with a die pad (93) which has a die (92) mounted thereon so that the heat generated by the die (92) can be dissipated through the heat spreader (91). Further, resin is generally applied to form the package body (94) for encapsulating the die (92), die pad (93) and the heat spreader (91) thereby forming a semiconductor package wherein the bottom face of the heat spreader (91) is exposed.
The above semiconductor package is able to dissipate heat generated by the die (92) with the use of the heat spreader (91). However, because the adhesion degree between copper and resin is relative low, the adhesion between the heat spreader (91) and the package body (94) is weak. Therefore, a tiny gap is likely to exist between the heat spreader (91) and the package body (94) so that moisture or contaminants may enter into the semiconductor package and damage the circuit therein. Further, in the semiconductor packaging process, a ground bonding wire (96) is usually connected to the die pad (93) to improve ground effect for the die (92). As a result, when the external lead (95) of the semiconductor device is electroplated in an electrobath, the exposed bottom face of the heat spreader (91) may be soldered because an electrical conductive path is formed from the external lead (95), bonding wire (97), ground bonding wire (96), die pad (93) to the heat spreader (91). Such a soldering to the heat spreader (91) is undesired, and therefore, there is a need for the above semiconductor package to be improved.